Boxes said to have contained a huge cache of explosives were loaded into a Mercedes by a man wearing only underwear, according to video footage shown in court yesterday. Police say the scantily clad man - who must be referred to as 'Person A' - was working with two of the three men accused of possessing almost 820kg of explosives, seized from an ivy-covered shack near the border. The seizure of 38 boxes of mixed ammonium nitrate, TNT and fuel oil by police on January 17 last year was Hong Kong's biggest explosives haul. Prosecution experts say the cache had the power to cause death and destruction over a 300-metre radius. Three men - Chan Sum-yau, 47, Wong Fung-kei, 44, and Lau Cheuk-fan, 32 - have denied a joint charge in the Court of First Instance of possessing explosives with intent to endanger life or property. Jurors watched almost three hours of video footage showing Wong, Lau, Person A and a man said to be Lau's brother, Lau Ting-fan, driving in and out of a high-security compound in Tai Wo, near Sheung Shui. Boxes were shown being moved to and from a silver Mercedes and a grey Toyota Land Cruiser, falsely registered under the name of an 86-year-old man. Footage at one point showed Person A wearing only a white vest, underpants and white gloves as he moved the boxes - marked 'big scallops' in Chinese - into the boot and back seat of the Mercedes. Acting Sergeant Lam Chun-kwong, 33, of the Criminal Intelligence Bureau, said he had spied on the walled compound on January 8 last year and identified all the men. 'I was observing from the upper reaches of the hillside, looking down towards [Tai Wo compound house number] 95b,' he said. 'Wong and Lau Ting-fan were wearing white gloves. Person A was shuffling the boxes with his feet . . . he was observing, looking around,' the witness said. The video showed Wong and the man said to be Lau Ting-fan in white gloves moving boxes from the Land Cruiser to the outside of the house. Some boxes were later seen being moved to the Mercedes and driven away. The case continues before Mr Justice Peter Nguyen.